The aim of this project is to elucidate the mechanism of glucocorticoid-induced lymphoma regression and to clarify the basis for resistance to steroid therapy in non-responsive tumors. The following approaches will be used: a) Investigation of the possible role of RNA synthesis and mRNA induction in the lympholytic process, using specific inhibitors, affinity chromatography and polyacrylamide gel electrophoresis; b) Comparison of specific glucocorticoid receptors in cytoplasmic and nuclear fractions derived from corticoid-sensitive and -resistant lymphoid tumors; c) Studies on the influence of glucocorticoid treatment on the activity of DNA-dependent RNA polymerase; d) Examination of the role of free fatty acids, energy metabolism and proteolytic enzymes in the lympholytic process itself.